Particle separator device for plating baths



Dec. 7, 1965 R. J. cLAuss ETAL.

PARTIGLE SEPARATOR DEVICE FOR PLATING BATHS 2 Sheets-Sheet 1 Filed Julyl5. 1961 D, 7, 1965 R. J. cLAuss E'rAl. 3,222,268

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United States Patent O 3,222,268 PARTICLE SEPARATQR DEVICE FOR PLATINGBATHS Richard J. Clauss, Allen Park, Roy Walter Klein, St. Clair,

and Leon I. Pianowski, Detroit, Mich., assignors, by

mesne assignments, to The Udylite Corporation, Warren, Mieli., acorporation of Delaware Filed July 13, 1961, Ser. No. 123,718 3 Claims.(Cl. 204 238) The present invention broadly relates to a mechanism forselectively separating extremely fine-sized particles and moreparticularly to a filtration device for filtering slurries havingextremely fine-sized particles therein in order to remove any extraneoussolids above a prescribed size range.

A large number of commercial processes employ slurries comprising aliquid incorporating extremely fine-sized insoluble particles suspendedtherethrough and which particles must be Imaintained within a controlledsize range necessitating the removal of deleterious larger particles andother extraneous matter which is introduced into the slurry during itsuse. In many instances the progressive buildup in concentration ofextraneous particles above a prescribed size range result in asubstantial reduction in the efficiency and performance `of the slurryeventually rendering it useless and it must therefore be discarded. Thisoftentimes represents a costly and time-consuming operation detractingfrom the overall efficiency of the process.

A typical example wherein slurries are employed is in the formation ofsatin-like high luster nickel plated finishes on base metals providingtherewith a high degree of protection against corrosive attack andconcurrently providing an attractive appearance. In electroplatingoperation of this type acidic aqueous slurries of a pH ranging fromabout 2 to about 6 ofthe Watts type e-mploying conventional solublenickel salts such as nickel sulfate, nickel chloride and nickelsulfamate, for example, and conventional brightener agents of the typeswell known in the art are provided with from about 10 grams up to about500 grams per liter of extremely fine-sized particles generally having aparticle size of less than about 5 microns and preferably less thanabout 2 microns and approaching colloidal dimensions. These particlesare insoluble and are wetted by the acidic bright or semibright nickelplating solution. The line-sized particles are suspended substantiallyuniformly through the bath and are incorporated in the layer ofelectro-deposited nickel on the surface of the base metal impartingthereto a satin-like finish.

The presence of extraneous larger size particles such as may result frompoorly cast nickel anodes which powder during use and disperse coarsemetallic particles of nickel and activated carbon in the bath result inthe formation of non-uniform and coarse satin finishes. It has thereforebecome necessary to find a mechanism and method for economicallyremoving such extraneous large size particles from the nickel bath andin other slurries having particles suspended therein of a controlledmaximum size which is both efficient, economical and provides thedesired degree of particle size selectivity.

It is accordingly a primary object of the present invention to providean improved filtration apparatus for filtering slurries and selectivelyremoving therefrom particles above a preselected size.

Another object of the present invention is to provide an improvedfiltration apparatus for removing solid particles greater than apredetermined size from a slurry which enables passage of all othersolids below that specific size range and which apparatus is of simpledesign, economical 3,222,268 Patented Dec. 7, 1965 ice manufacture,durable operation and simple control, and which is quickly a'ssemblableand disassemblable for cleaning and maintenance.

The foregoing and other 4objects of the present invention are achievedby providing a filtration apparatus comprising a receptacle having atleast one substantially horizontal tier removably mounted therein of a4filtering me dium having a predetermined porosity enabling passage of aslurry therethrough whi-ch selectively removes extraneous particlesabove a preselected size.

Other objects and advantages of the present invention will becomeapparent from the following detailed description taken in conjunctionywith the accompanying drawings, wherein:

FIGURE 1 is a side elevation View of a typical liquid treatingreceptacle incorporating a filtration apparatus adjacent thereto whichis constructed in accordance with the preferred embodiments of thisinvention;

FIG. 2 is a transverse vertical sectional View through the filtrationapparatus shown in FIGURE 1 and taken substantially along the line 2 2thereof;

FIG. 3 is a transverse horizontal view through the inlet nozzle anddeflector of the filter apparatus shown in FIG. 2 and taken along theline 3 3 thereof, and

FIG. 4 is a transverse horizontal View through the filter apparatusabove the top tier thereof as shown in FIG. 2 and taken substantiallyalong the line 4 4 thereof.

Referring now to the drawings and as may be best seen in FIGURE l, atypical self-contained installation of a filtration system m-ountedadjacent to a liquid receptacle or tank 10 is illustrated which isadapted to loperate intermittently or continuously as desired, and tosuccessfully remove solid particles in the slurry larger than apredetermined size but still enable the high solids content of smallersized particles in the slurry having a size range broadly ranging fromabout l5 microns to a size approaching colloidal dimensions such as .1micron to pass through and be recirculated back into the tank. Thefiltration sysem shown in FIGURE 1 is applicable to a wide variety rofdifferent slurries including aqueous alkaline or acidic slurries havinghigh solid contents such as concentrations ranging from about 10 gramsup to about 500 grams per liter.

The extremely fine-sized particles contained in the slurry can compriseany one of a number of solids including certain sulfates, carbonatos,phosphates, oxalates, silicates, metallic oxides, carbides, silicides,nitrides, fluorides, sulfides, -of a variety of metals includingaluminum, magnesium, boron, calcium, strontium, barium, alkali metalearths, titanium, manganese, zirconium, iron, chromium, and the like.Substantially insoluble particles which are wetted by the acidic nickelplating solutions of a type employed for electrodepositing a satin-likenickel finish on the surfaces `of a base metal include insolublesilicates of aluminum, magnesium, boron, calcium, strontium and barium,and lmixed silicates of these metals, as well as certain sulfates,carbonates, phosphates, and oxalates of alkaline earth metals, barium,strontium, and calcium, as well as certain oxides, carbides, silicides,nitrides, fluorides, and Suldes of the group consisting of siliconcarbides, boron carbide, titanium carbide, silicon dioxide, manganeseoxide, titanium oxide, zirconium oxide, aluminum oxide, ferrie oxide,chromic oxide, boron nitride, calcium fiuoride, str-onium fluoride,barium fluoride, zinc sulfide, cadmium sulfide, and iron silicide. Ofthe foregoing, kaolin (china clay) is particularly satisfactory andfinely powdered glass is also suitable when employed in size rangesbelow about 5 microns and preferably below about 2 microns to as low -asabout .1 micron and smaller.

In the self-contained system shown in FIGURE 1, the tank 10 is providedwith suitable agitation means (not shown) for maintaining the insolubleparticles in the slurry substantially uniformly distributedtherethrough. Withdrawal of the slurry from the tank is achieved by aperforated suction tube 12 mounted along the side wall of the tankhaving a plurality of perforations 14 therein through which the slurryenters at spaced intervals throughout the entire depth of the tank. Theupper end of the suction tube 12 is removably connected to an inlet pipe16 connected to the suction side of a pump 18 which is drivinglyconnected to a motor 20 mounted on a supporting frame 22. The slurry isdischarged from the discharge side of the pump 18 through an outlet pipe24 which is removably connected to an inlet pipe 26 of a filterapparatus 28. The slurry passes through the filter apparatus 2S duringwhich any large particles entrained in the slurry above a preselectedsize range are removed and the filtered slurry and extremely fine-sizedparticles therein are returned to the tank 10 through a drain or adischarge pipe 3ft at the base of the filter apparatus 28. The operationof the filtration system can be accomplished continuously or on anintermittent basis depending on the rate of buildup of undesirable largeparticles and the concentration thereof which can be tolerated in theslurry.

The filter apparatus 28 as best shown in FIGS. 2 through 4, comprises areceptacle such as a cylindrical drum 32 including a base or bottommember 34. The drum 32 may be open at the top when gravity flow of theslurry is employed. The drum may be of any suitable material ofsatisfactory strength such as steel, for example, and if subjected toalkaline or acidic slurries, such as an acidic nickel plating slurry ofthe hereinbefore mentioned type then the interior surfaces of the drum32 are preferably provided with a protective coating 36 such as acoating of polyvinyl chloride plastic, for example, to prevent corrosiveattack thereof. Alternatively, the drum in such case can be constructedof a plastic material such as reinforced polyester or phenolic resin,for example, which is resistant to the alkaline and acidic solutions incontact therewith. In this connection, it will also be appreciated thatthe suction tube 12, the inlet and outlet pipes 16 and 24, and the inletpipe 26 to the filter, should be of a suitable non-corrosive materialsuch as rigid polyvinyl chloride plastic, for example, to resistcorrosive attack of any heated alkaline and acidic solutions to whichthey may be exposed. The pump 18 similarly may be of suitable plastic orstainless steel alloy to resist corrosive attack of the acidic andalkaline slurries.

Removably positioned within the interior of the drum 32 is a pedestal 38including a base 40 disposed in bearing contact against the bottommember 34 and a rod 42 affixed thereto and extending substantiallyperpendicular therefrom and positioned in substanital axial alignmentwith the longitudinal axis of the drum 32. The pedestal 38 is providedwith the protective coating 36 over the surface thereof to preventcorrosive attack by any acidic or alkaline slurries to which it may beexposed. A series of tubular cylindrical spacer sleeves 44 are slidablydisposed around the rod 42 of the pedestal 38 and are adapted to supporta series of trays 46 in substantially horizontal and appropriatelyvertical spaced relationship. Each of the trays 46 are of a perforatedconstruction and may comprise an expanded sheet of metal of theconfiguration as shown in FIG. 4. The surfaces of the trays 46 aresimilarly provided with a layer of the protective coating 36 thereover.The central portion of the trays 46 are preferably rigidified byincorporating an annular collar or washer 48 having a central aperturetherethrough which slidably overlies the rod 42 of the pedestal 38.

The upper projecting end of the rod 42 is provided with a threadedportion which is adapted to be threadably engaged in a threaded bore 50extending upwardly and axially along substantially the longitudinal axisof a combination nozzle and deflector member 52 which is disposedcentrally of and adjacent to the upper surface of the top filtering tierof the filter apparatus 28. The upper end of the combination nozzle anddeflector member 52 as viewed in FIG. 2 is provided with a threadedcollar adapted to threadably engage a coupling 54 which in turn 4isthreadably engaged to the inlet pipe 26 extending axially downwardlythrough the top of the drum 32. The upper threaded fiange of the nozzleand deflector member 52, as is best shown in FIGS. 2 and 3, is providedwith a plurality of axial nozzles 56 therethrough which are located in acircular arrangement and can vary in number and size depending on thespecific capacity and rate of flow of slurry through the filter. Thenozzles 56 are disposed in communication with the interior of thecoupling 54 and inlet pipe 26 and serve to discharge the slurry enteringthe filter apparatus tangentially along the downwardly and outwardlyfiaring surface of the nozzle and deflector member 52 so as to directthe slurry in a radial direction as indicated by the arrows in FIG. 4achieving maximum utilization of the surface of the upper tier of thefilter.

The radial discharge of the slurry as a result of the deflectingtendency of the nozzle and defiector member 52 also serves to sweep theinner annular surface and wash any large solid particles entrappedthereon toward the peripheral edges of the filter forming a sludgebuild-up generally indicated at 58. This discharge pattern serves as aself-cleaning feature and increases the efficiency of the filter as wellas increasing the duration between the cleansing of the filtering tiersto remove the sludge 58 therefrom. A number of suitable spacer washers57 can be disposed between the upper filtering tier and the base of thenozzle and defiector member 52 so as to adjust the relative elevationbetween the deflecting surface thereof and the upper surface of thefilter medium positioned on the upper ltray 46 achieving the desiredradial impingement of the slurry discharged through the nozzles 56.

In the specific filter shown in the drawings, three trays 46 areemployed forming three filtering tiers each of which is provided with adifferent filter medium overlying the upper surface thereof. The topfiltering tier as viewed in FIG. 2 comprises a coarse, relatively openweave material 59 which is formed in the shape of a shallow pancomprising a circular base 60 having an upstanding side wall 62extending around the periphery of the base 60 and integrally affixedthereto. The side wall 62 prevents the sludge accumulation 58 along theouter portions of the first tier from overflowing and passing downwardlythrough the adjacent tiers.

The open weave material 59 is preferably constructed from a chemicallyresistant fiber which is inert to and unaffected by the acidic oralkaline slurries impinging thereon. A material which has been foundsurprisingly effective for filtering deleterious large sized particleshaving a size range of about 50 microns or greater in the acidicsatin-like nickel plating slurries hereinbefore described andconcurrently allowing the relatively high solids content of fine-sizedinsoluble particles to pass therethrough comprises an open weave Sarancloth designated as fabric 1057-000 of a 20' ounce per yard weightmanufactured by the Chicopee Manufacturing Corporation. This fabric ischaracterized as being substantially inert to the acidic slurriesimpinging thereon and comprises a three dimensional matrix having adepth of about 1A inch composed of interwoven rnonofilament Saran fibersof about 12 mil filament diameter woven in a satin weave patternproviding nominal openings which prevent passage of spherical glassbeads of about 250 microns in diameter. The surface structure of thisSaran fabric enables the defiected impinging stream of the slurry towash any large particles retained thereon toward the periphery of thematerial 59 resulting in an accumulation of sludge 58 as indicated inFIG. 2 providing continued high efficient filtration through the innercircular portion thereof. Satisfactory removal of objectionable largesolids from the aforementioned satin-like nickel plating solution cansatisfactorily be accomplished by employing a single filtering tierprovided with the open weave Saran cloth or fabric designated 1057-000.

It is usually preferred, however, to `employ two, three, or morefiltering tiers each of which employs filtering medium thereon having aprogressively smaller porosity to remove therefrom particles of a size`between that which passes through the first filtering medium and theparticles of a preselected size which are intended to be returned to theslurry tank. In the filter shown in FIG. 2, the middle tier is providedwith a filter medium 64 of an open mesh construction having a porositysmaller than that of the upper tier filter medium 59. Materials suitablefor this purpose include a Saran woven cloth designated 1017- 000supplied by the Chicopee Manufacturing Corporation which is an 1111/2ounce/yard fabric woven of Saran filaments of 8 mil diameter in a basketweave and which is effective to retain spherical glass beads of about 50microns in diameter. This fabric is effective to retain irregularlyshaped particles which pass the material 59 but still permit thedesirable solids of a particle size of less than about 20 microns in theslurry to pass therethrough. An alternate satisfactory filter medium forthe middle tier can comprise a chemically resistant glass wool or otherwool comprised of ya fiber which is resistant to attack by any alkalineor acidic slurries to which it may be exposed and which is formed in athree-dimensional mat having an irregular porosity. A typical exampleincludes a mat comprised of Dynel fibers manufactured by the UnionCarbide Corporation which retains relatively fine solid particles butenables the desirable insoluble particles of a size of about microns orless to pass through unhampered. The bottom tier is provided with afilter medium 66 which is of still a finer porosity and may, forexample, comprise two layers of a glass wool or Dynel wool of the typeemployed for the middle tier filter medium 64 which is effective toremove particles greater than about 10 microns.

The fiow of the slurry through the tiered filter shown in FIG. 2 isachieved by gravity wherein the slurry discharged in a radial pattern onthe upper tier drips through the filter medium 59 and tray 46 thereofand thence downwardly and successively through the middle tier and lowertiers and finally flows out of the base of drum 32 through the dishargepipe 30 and is returned to the tank 10. The filter is used continuouslyor intermittently until the accumulation of the sludge 58 along theVupper filter medium 59 reaches a magnitude wherein the sludge itselfserves as a filter medium entrapping the extremely fine-sized particlesin the slurry which impinges thereon. If this condition progresses tothe extent that the filter becomes plugged, the slurry may accumulateuntil it reaches the level of an overflow pipe 68 in the upper portionof the drum 32 from which it is returned back to the tank 10.

The filter is simply cleaned by disconnecting the inlet pipe 26 from theoutlet pipe 24 and thereafter withdrawing the entire inner assembly ofthe filter from the drum 32. The filter medium on each of the trays isthen subjected to water immersion or a high pressure spray to back-washand dislodge any large particles accumulated thereon. After the filtermedia have been cleaned, the filter is reassembled merely by reinsertingthe inner assembly in the drum and connecting the inlet pipe 26 to theoutlet pipe 24.

The filter apparatus hereinbefore described can also be satisfactorilyemployed by placing it in series, either before or after otherconventional filter apparatus to preliminarily remove large sizeparticles or as a safeguard in the event of failure of the principalfilter. While it will be apparent that the preferred embodiments hereinillustrated are well calculated to fulfill the objects above stated, itwill be appreciated that the invention is susceptible to modification,variation and change without departing from the proper Scope or fairmeaning of the subjoined claims.

What is claimed is:

1. In a filtration apparatus for removing insoluble parvticles in aslurry above a preselected size the combination comprising a receptacle,inlet means for supplying a `flow of slurry having a finely particulatedsolids content `ranging from Yabout 10 grams to about 500 grams perliter of a particle size predominantly less than about l5 microns,filter means disposed transversely of said receptacle and positioned ina substantially horizontal plane, said filter means comprising athree-dimensional open weave cloth having a porosity so as to retainspherical solids of a size greater than about 250 microns and formed inthe configuration of a pan comprising a horizontal base portion and anupstanding wall portion connected to and extending along the peripheryof said base portion, combination nozzle and deflector means disposedadjacent to the upper surface of said filter means for discharging theslurry from said inlet means in an outwardly directed radial directionabove substantially the center portion of said filter means, saiddeflector means including a body defining an arcuate downwardly andoutwardly flared surface of a circular cross section, said nozzle meansincluding substantially vertically oriented discharge means disposedadjacent to the upper end of said deffector means for discharging theslurry downwardly along said flared surface and in a radial and outwarddirection from the circular peripheral edge thereof in the form of asubstantially continuous curtain across the upper surface of said filtermeans, and drain means at the lower portion of said receptacle fordischarging the filtered slurry from said filtration apparatus.

2. In a ltration apparatus for removing insoluble particles above apreselected size from a slurry, the combination comprising a receptacle,inlet means for supplying a flow of slurry having a finely particulatedsolids content ranging from about lO grams to about 500 grams per literof a particle size predominantly less than about l5 microns, filtermeans comprising a plurality of tiers of filter medium disposed invertically spaced relationship one above the other and in substantiallyhorizontal planes, said lter medium of sai-d tiers having aprogressively decreasing porosity progressing from the uppermost of saidtiers to the lowermost of said tiers and operative to retain solidsthereon of a size greater than about l5 microns entrained in the slurryand to pass the liquid and remaining solids content therein through saidfilter medium by gravity fiow, each of said tiers comprising aperforated support member and an overlying filter medium supportedthereon, a pedestal supported on the base of said receptacle andextending upwardly therefrom through substantially the midpoint of eachof said tiers, spacer means associated with said pedestal andcooperating with adjacent ones of said tiers for maintaining said tiersin appropriately vertically spaced relationship, combination nozzle anddeflector means removably mounted on the upper end of said pedestaladjacent to the uppermost of said tiers for clamping said tiers betweensaid spacer means and for discharging the slurry from said inlet meansin an outwardly directed radial direction above substantially the centerportion of said filter medium on said uppermost of said tiers, drainagemeans in the lower portion of said receptacle for discharging thefiltered slurry from said receptacle, and overflow means in the upperportion of said receptacle above said uppermost of said tiers.

3. In a nickel plating apparatus for electrodepositing a satin-likenickel finish on the surface of a base metal, the combination comprisinga tank, a liquid slurry in said tank including a soluble nickel salt andan extremely finesized insoluble particulated solids content suspendedtherein ranging in concentration from about l0 grams to about 500 gramsper liter and having a particle size predominantly less than about 5microns, pumping means including inlet means immersed in said slurry forwithdrawing a quantity thereof, a filter apparatus disposed adjacent tosaid tank, conduit means connected to said pumping means for supplying aflow of slurry to said filter apparatus, said filter apparatuscomprising a receptacle, filter means disposed transversely of saidreceptacle and positioned in a substantially horizontal plane,combination nozzle and deflector means for discharging said slurry fromsaid conduit means in an outwardly directed radial direction adjacent tothe upper surface of an above substantially the center portion of saidlter means, said deilector means including a body defining an arcuatedownwardly and outwardly flared surface of a circular cross section,said nozzle means including substantially vertically oriented dischargemeans disposed adjacent to the upper end of said deliector means fordischarging the slurry downwardly along said ared surface and in aradial and outward direction from the circular peripheral edge thereofin the form of a substantially continuous curtain across the uppersurface of said filter means, said filter means having a porosity toretain solids thereon of' a size greater than about l0 microns entrainedin said slurry and to pass the liquid and remaining solids content ofsaid slurry by gravity flow through said filter means, and drain meansat the lower portion of said receptacle for discharging the filteredsaid slurry from said filter apparatus to said tank.

References Cited by the Examiner UNITED STATES PATENTS 794,840 7/1905Barker 210-456 X 1,064,243 6/1913 Naegelen et al. 210-335 1,561,60211/1925 Gauss 204-238 2,232,025 2/1941 Glisan 210--339 3,023,905 3/1962McDougal et al 210-172 FOREIGN PATENTS 625,151 2/1936 Germany.

REUBEN FRIEDMAN, Primary Examiner.

GEORGE D. MITCHELL, EUGENE F. BLANCHARD,

Examiners.

3. IN A NICKEL PLATING APPARATUS FOR ELECTRODEPOSITING A SATIN-LIKENICKEL FINISH ON THE SURFACE OF A BASE METAL, THE COMBINATION COMPRISINGA TANK, A LIQUID SLUURRY IN SAID TANK INCLUDING A SOLUBLE NICKEL SALTAND EXTREMELY FINESIZED INSOLUBLE PARTICULATED SOLIDS CONTENT SUSPENDEDTHEREIN RANGING IN CONCENTRATION FROM ABOUT 10 GRAMS TO ABOUT 500 GRAMSPER LITER AND HAVING A PARTICLE SIZE PREDOMINANTLY LESS THAN ABOUT 5MICRONS, PUMPING MEANS INCLUDING INLET MEANS IMMERSED IN SAID SLURRY FORWITHDRAWING A QUANTITY THEREOF, A FILTER APPARATUS DISPOSED ADJACENT TOSAID TANK, CONDUIT MEANS CONNECTED TO SAID PUMPING MEANS FOR SUPPLYING AFLOW OF SLURRY TO SAID FILTER APPARATUS, SAID FILTER APPARATUSCOMPRISING A RECEPTACLE, FILTER MEANS DISPOSED TRANSVERSELY OF SAIDRECEPTACLE AND POSITIONED IN A SUBSTANTIALLY HORIZONTAL PLANE,COMBINATION NOZZLE AND DEFLECTOR MEANS FOR DISCHARGING SAID SLURRY FROMSAID CONDUIT MEANS IN AN OUTWARDLY DIRECTED RADIAL SUBDIRECTION ADJACENTTO THE UPPER SURFACE OF AN ABOVE SUBSTANTIALLY THE CENTER PORTION OFSAID FILTER MEANS, SAID DEFLECTOR MEANS INCLUDING A BODY DEFINING ANARCUATE DOWNWARDLY AND OUTWARDLY FLARED SURFACE OF A CIRCULAR CROSSSECTION, SAID NOZZLE MEANS INCLUDING SUBSTANTIALLY VERTICALLY ORIENTEDDISCHARGE MEANS DISPOSED ADJACENT TO THE UPPER END OF SAID DEFLECTORMEANS FOR DISCHARGING THE SLURRY DOWNWARDLY ALONG SAID FLARED SURFACEAND IN A RADIAL AND OUTWARD DIRECTION FROM THE CIRCULAR PERIPHERAL EDGETHEREOF IN THE FORM OF A SUBSTANTIALLY CONTINUOUS CURTAIN ACROSS THEUPPER SURFACE OF SAID FILTER MEANS, SAID FILTER MEANS HAVING A POROSITYTO RETAIN SOLIDS THEREON OF A SIZE GREATER THAN ABOUT 10 MICRONSENTRAINED IN SAID SLURRY AND TO PASS THE LIQUID AND REMAINING SOLIDSCONTENT OF SAID SLURRY BY GRAVITY FLOW THROUGH SAID FILTER MEANS, ANDDRAIN MEANS AT THE LOWER PORTION OF SAID RECEPTACLE FOR DISCHARGING THEFILTERED SAID SLURRY FROM SAID FILTER APPARATUS TO SAID TANK.